The effectiveness of radiation in preventing restenosis following angioplasty was demonstrated in a 1995-1996 study conducted by Paul Teirstein of Scripps Clinic in which sources prepared from Ir-192 were used in patients previously receiving balloon angioplasty and stent implantation (Teirstein et al., N. Engl. J. Med., 336:1697-1703 (1997)). The study showed that in patients receiving the radioactive source treatment, the restenosis rate dropped to 16.7% in the radiation treated group versus 53.6% of the patients in the "placebo" group not receiving radiation.
One of the problems with the current intra-coronary radiation devices (ICRD) is the exposure of the source to the medical personnel. For example, currently after administration of the Ir-192 source, the operators and physicians have to leave the treatment room to avoid getting an excessive dose.
Sr-90 and P-32 are among the other ICRD sources currently in clinical trials. Both of these sources has serious limitations. Sr-90 is problematic due to its high toxicity in the event of source and catheter rupture in the patient. P-32 may have a less than optimum beta energy to provide the proper dose profile, at least in larger calcified plaque occluded arteries.
It is desirable to develop an ICRD which can provide a 4:1 dose at 1 mm and 4 mm respectively in the artery, have a sufficiently long half-life to allow multiple patient use at minimum cost, and have minimum radiation exposure to the medical personnel.